The present invention relates generally to interventional devices for medical procedures. More particularly, the invention relates to selective treatment of ischemic or infarcted myocardium, with mechanical and electromagnetic energy functional devices, for simulating extension of the boundary between myocardial and endocardial layers within the heart. The invention is particularly adapted for simulating extension of the endocardial layer into the myocardium and for treating hibernating tissue zones.
Transmyocardial Revascularization
In the treatment of heart disease, one method of improving myocardial blood supply is called transmyocardial revascularization (TMR), the creation of channels in the myocardium of the heart. The procedure using needles in a form of surgical xe2x80x9cmyocardial acupuncturexe2x80x9d has been used clinically since the 1960s. Deckelbaum. L. I., Cardiovascular Applications of Laser Technology, Lasers in Surgery and Medicine 15:315-341 (1994). The technique relieves ischemia by causing angiogenesis and allowing blood to pass from the ventricle through the channels either directly into other vessels communicating with the channels or into myocardial sinusoids which connect to the myocardial microcirculation.
In the reptilian heart, perfusion of the myocardium occurs via communicating channels between the left ventricle and the coronary arteries. Frazier, O. H., Myocardial Revascularization with Laserxe2x80x94Preliminary Findings, Circulation, 1995; 92 [suppl II]:II-58-II-65. There is evidence of these communicating channels in the developing human embryo. In the human heart, myocardial microanatomy involves the presence of myocardial sinusoids. These sinusoidal communications vary in size and structure, but represent a network of direct arterial-luminal, arterial-arterial, arterial-venous, and venous-luminal connections. This vascular mesh forms an important source of myocardial blood supply in reptiles but its role in humans is poorly understood.
This is confirmed by recent research and a recent article. A greater proportion of reptilian endocardium and myocardium is supplied with oxygenated blood from the left ventricle itself, as opposed to the coronary arteries. Reptilian endocardium is relatively thickerand more-sponge-like than human myocardium, deriving from the extensive network of sinusoids and large channels emanating from the left ventricle and richly innervating the myocardium, thereby providing an increased effective surface area for blood flow, also known as xe2x80x9cwashingxe2x80x9d, and transfer of oxygen and nutrients to the myocardium. In the research protocol, after explanation and instrumentation, alligator hearts were perfused via the coronary arteries as well as via xe2x80x9cwashingxe2x80x9d from the left ventricle. Using microspheres to estimate myocardial perfusion in the beating hearts, it was shown that although the epicardium was well perfused by the coronary arteries, a significant proportion of endocardial perfusion was from the ventricular chamber rather than the coronary arteries. Kohmoto, T. et al, Assessment of Transmyocardial Perfusion in Alligator Hearts, Circulation, Vol. 95, No. 6, Mar. 18, 1997.
Apparatus and methods for extending the thickness of endocardial tissue, and increasing oxygen and nutrient transport by washing of blood through the left ventricle, are virtually unknown. Conventionally, a process called transmyocardial revascularization is directed to forming a discrete number of spaced-apart channels, surgically from an epicardial surface through epicardium (TMR) or percutaneously through the left ventricle directly into myocardial tissue (PTMR). However, conventional TMR/PTMR does not create a dense pattern of stimulus injuries placed to simulate extension of the porous endocardium. TMR also does not focus treatment on the endocardial/myocardial boundary regions where ventricular washing flow via endocardium can enhance angiogenesis. Furthermore, treating hidden zones of hibernating, infarct-damaged or other types of tissue with a denser pattern of stimulation pathways is desirable and may be accomplished using the apparatus and methods for selective treatment of the endocardial/myocardial boundary.
Thus, it is an advantage of the present invention to provide an apparatus and method of use for selective myocardial revascularization, which overcomes the limitations of the prior art.
It is another advantage of the present invention to provide an apparatus and method especially adapted for selective treatment of hibernating tissue, infarct-damaged or other types of tissue best treated selectively.
It is a further advantage of the present invention to provide an apparatus with one or more fiber optic laser delivery means for effecting selective treatment of the endocardial/myocardial boundary.
It is a further advantage of the present invention to provide a catheter apparatus for placement within a heart chamber, organ aperture or other body opening, the apparatus having at least one lumen for guiding an energy delivery device or mechanical device to selected surfaces of the heart, heart chamber, organ aperture or other body opening for treatment thereon, particularly adapted for selective treatment of the endocardial/myocardial boundary.
Yet an additional advantage and object of the present invention is to provide a multiple channel type surgical or minimally invasive surgical apparatus for percutaneous, surgical or minimally invasive surgical use for creation of a plurality of stimulation zones or myocardial channels co-extending from a single epicardial, myocardial or endocardial point or position.
Another advantage and object of the present invention is to provide a surgical apparatus for performing selective treatment from an epicardial surface.
It is a further advantage of the present invention to provide an optimized amount of trauma or means of injury specific to or within a boundary, such as between endocardium and myocardium, or between infarct and non-infarct boundaries, naturally provided with ventricular blood via the highly vascularized endocardium.
Another advantage of the present invention is to treat boundary regions by minimizing or otherwise preventing undesirable and unnecessary lasing or other mechanical damage to existing endocardium, or epicardium, to gain access to the boundary region by piercing through the endocardium or epicardium to a depth which allows creation of the injury only at the selected boundary region.
In summary, the present invention is an apparatus for placement within a heart chamber, organ aperture, chest cavity or other body opening. The apparatus has at least one lumen for guiding an energy delivery device or mechanical device to selected surfaces of a heart or heart chamber for treatment thereon. The distal tip of the device has one or more functional devices extending therefrom, optionally having a deflection control mechanism therein. The apparatus can be used in conjunction with a fiber optic or other laser delivery means, mechanical intervention means, radio frequency device, microwave device, ultrasound device or fluid jets.
In a preferred embodiment, the invention comprises a transluminal catheter having a proximal end and a distal end and at least one lumen with a handle portion at the proximal end and a treatment device deflecting mechanism, such as a ball or cone, at the distal end. One or more, preferably several, treatment devices can be advanced out the distal end of the lumen, and deflected by the ball or cone at an angle to provide a relatively dense multiple pattern of treatment points from adjacent a single site. By forming a large number of mechanical or energy incisions through the endocardium and in myocardium, i.e. in the endocardial/myocardial boundary, the treated myocardial area will have endocardium-like properties, including providing a greater surface area and higher efficiency of oxygen and nutrient transfer via blood washing of the untreated myocardium through the intact and densely profused endocardium which receives a large amount of oxygenated blood via the ventricle.
In a preferred embodiment, the invention is a surgical and minimally invasive surgical handpiece with advancement mechanism to allow insertion of an energy or mechanical device through the epicardial surface to a desired depth where deployment of multiple treatment devices can occur to create a relatively dense pattern of injury in several millimeters of myocardium adjacent a border with endocardium and into the endocardium.
A novel method of locating and treating zones of myocardial tissue, such as adjacent a boundary, which have been damaged by infarct or otherwise is also disclosed using described apparatus. Such hidden or hibernating zones are treatable by extending individual optical fibers or fiber bundles therein, so as to effectively create a dense pattern of injury from the ventricle through healthy endocardial tissue, or from the epicardium, into the hibernating zones. The method treats boundary regions by minimizing or otherwise preventing undesirable and unnecessary lasing or other mechanical damage to existing endocardium to gain access to the boundary region. Piercing tools are described to facilitate advancement to the selected boundary prior to creation of the injury.
Numerous other advantages and features of the present invention will become readily apparent from the following detailed description of the invention and the embodiments thereof, from the claims and from the accompanying drawings.